Chapter 503 of the "Fairy Tail" manga may finally reveal what Natsu's tumor is.

According to a report by Game N' Guide, there are discussions on Reddit speculating that the tumor could be a sign that Natsu is turning into an E.N.D. There are also speculations that the tumor is actually one stage of Natsu turning into a dragon.

Whichever the case, it is expected that the transformation will come into fruition either because the tumor is triggered by Dimaria's torture, or even because Natsu has been excessively using his Dragon Slayer Magic.

A rescue party is also expected to come to the aid of Natsu and Lucy to save them from Dimaria. 

On the other hand, Brandish is expected to join the party to return the favor given to her when she received medical attention when she needed it.

A report by itech Post revealed that chapter 503 will be entitled "The Last Sight I Beheld" and supported the rumor that Brandish will be an ally in this episode. However, instead of simply returning a favor, the report hinted that there is a deeper reason for Brandish's eagerness to help Natsu's party.

It is believed by some fans that Brandish actually has some unfinished business with Dimaria, and she will learn something about Natsu's E.N.D. that will finally convince her to switch sides. Unfortunately for Dimaria, it seems that that the trigger to Natsu's tumor will result in him turning into a monster and she will be the first one to experience his wrath.

Meanwhile, there are predictions that Zera could be Mavi's last hope for salvation. Zera — who is actually part of Mavi's subconscious — might end up protecting Mavi because she is not affected by Invel's magic.

Chapter 503 of the "Fairy Tail" manga is expected to be released by late this week or early next week.